We can twist open the side of the drain outlet of the floor heating, and then connect a relatively thin pipe from the mouth of the drain pipe to the back basket to release water, and put more water in the line of air.
Step 1: Close No. 2 water valve (water valve handle and water pipe perpendicular to the close)
Step 2: Close No. 4 water valve Step 3: Open the small iron cap at No. 8, 9, 10, and 11 positions, and use a hex wrench to tighten and close each water valve.
Step 4: Connect the prepared water pipe to the No. 7 water outlet, and then place it in the basin or sink.
Step 5: Use a hex wrench to loosen the water valve under the size 8 small iron cap cap to its maximum.